Westinghouse Electric Corporation

Siemens Westinghouse Power Corporation

Siemens Energy, Inc.

Roswell J Ruka

Prabhakar Singh

Lewis J Kuo

Arnold O Isenberg

Subhash C Singhal

Richard A Basel

Raymond A George

Theodore R Vasilow

Raymond J Bratton

Charles J Spengler

Gong Zhang

Li Baozhen

Robert Draper

Paolo R Zafred

Kevin Huang

Gregory E Zymboly

George R Folser

Robert G Charles

Kevin P Litzinger

William G Carlson

Alfred R Pebler

Shailesh D Vora

Vinod B Doshi

Srikanth Gopalan

Charles A Hager

Barry R Rossing

Baozhen Li

Kathryn A Warner

A plasma sprayed ceramic-metal fuel electrode is provided. The fuel electrode has particular application in connection with a solid oxide fuel cell used within a power generation system. The fuel cell advantageously comprises an air electrode, an electrolyte formed on at least a portion of the air electrode, a plasma sprayed ceramic-metal fuel electrode formed on at least a portion of the electrolyte, and an interconnect layer to connect adjacent cells in a generator.

Plasma sprayed ceramic-metal fuel electrode

An intermediate temperature solid oxide fuel cell structure capable of operating at from 600&#xb0; C. to 800&#xb0; C. having a very thin porous hollow elongated metallic support tube having a thickness from 0.10 mm to 1.0 mm, preferably 0.10 mm to 0.35 mm, a porosity of from 25 vol. % to 50 vol. % and a tensile strength from 700 GPa to 900 GPa, which metallic tube supports a reduced thickness air electrode having a thickness from 0.010 mm to 0.2 mm, a solid oxide electrolyte, a cermet fuel electrode, a ceramic interconnection and an electrically conductive cell to cell contact layer.

Tubular solid oxide fuel cells with porous metal supports and ceramic interconnections

A solid oxide fuel cell generator is provided for electrochemically reacting a fuel gas with a flowing oxidant gas at an elevated temperature to produce power. The generator includes a generator section receiving a fuel gas and a plurality of elongated fuel cells extending through the generator section and having opposing open fuel cell ends for directing an oxidant gas between opposing plena in the generator. A sealant defines a seal on the fuel cells adjacent at least one of the fuel cell ends. The sealant is a modified lanthanum borate aluminosilicate glass composition having a minimal amount of boron oxide and silica, and in which the sealant maintains substantially constant physical characteristics throughout multiple thermal cycles.

Solid oxide fuel cell generator including a glass sealant

A fuel cell for a fuel cell generator including a housing including a gas flow path for receiving a fuel from a fuel source and directing the fuel across the fuel cell. The fuel cell includes an elongate member including opposing first and second ends and defining an interior cathode portion and an exterior anode portion. The interior cathode portion includes an electrode in contact with an oxidant flow path. The exterior anode portion includes an electrode in contact with the fuel in the gas flow path. The anode portion includes a catalyst material for effecting fuel reformation along the fuel cell between the opposing ends. A fuel reformation control layer is applied over the catalyst material for reducing a rate of fuel reformation on the fuel cell. The control layer effects a variable reformation rate along the length of the fuel cell.

Fuel cell generator with fuel electrodes that control on-cell fuel reformation

A solid oxide fuel cell generator ( ), containing tubular fuel cells ( ) with interior air electrodes ( ), where a supporting member ( ) containing a plurality of holes ( ) supports oxidant feed tubes ( ), which pass from an oxidant plenum ( ) into the center of the fuel cells, through the holes ( ) in the supporting member ( ), where a compliant gasket ( ) around the top of the oxidant feed tubes and on top ( ) of the supporting member ( ) helps support the oxidant feed tubes and center them within the fuel cells, and loosen the tolerance for centering the air feed tubes.

Air feed tube support system for a solid oxide fuel cell generator

A fuel cell structure (,) is provided, having a pre-sintered nickel-zirconia fuel electrode (,) and an air electrode (,), with a ceramic electrolyte (,) disposed between the electrodes, where the pre-sintered fuel electrode (,) contains particles selected from the group consisting of nickel oxide, cobalt and cerium dioxide particles and mixtures thereof, and titanium dioxide particles, within a matrix of yttria-stabilized zirconia and spaced-apart filamentary nickel strings having a chain structure, and where the fuel electrode can be sintered to provide an active solid oxide fuel cell.

Fuel electrode containing pre-sintered nickel/zirconia for a solid oxide fuel cell

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Solid oxide fuel cell operable over wide temperature range

Interfacial material for solid oxide fuel cell

An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

Air electrode composition for solid oxide fuel cell

An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La.sub.w Ca.sub.x Ln.sub.y Ce.sub.z MnO.sub.3, wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics.

Lanthanum manganite-based air electrode for solid oxide fuel cells

A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation.

Sintered electrode for solid oxide fuel cells

A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators.

Low cost stable air electrode material for high temperature solid oxide

A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

Oxygen sensor for monitoring gas mixtures containing hydrocarbons

An apparatus and method for storing electrical energy as chemical energy and recovering electrical energy from stored chemical energy. A solid oxide electrolyte electrochemical cell is operated in two modes. The first, energy storage, mode comprises steps of: (A) supplying electrical energy and steam to a solid oxide electrolyte electrochemical cell operating between 600.degree. C. and 1200.degree. C. as an electrolysis cell, to produce H.sub.2 and O.sub.2 ; (B) passing the H.sub.2 gas so produced into an energy storage reactor containing iron oxide, to produce iron metal and steam; (C) recirculating the steam produced in the energy storage reactor to the cathode of the electrolysis cell; and (D) repeating steps (A) to (C) until the iron oxide is converted to iron metal, for chemical storage of electrical energy. The second, energy recovery, mode comprises steps of: (E) supplying steam to the energy storage reactor containing iron metal, to produce iron oxides and H.sub.2 gas; (F) passing this H.sub.2 gas to the fuel anode of an electrochemical cell operating as a fuel cell, and supplying O.sub.2 gas to the air cathode of the electrochemical cell, to produce electrical energy and steam at the fuel anode; (G) recirculating the steam so produced to the energy storage reactor bed; (H) repeating steps (E) to (G) until the iron metal is converted to iron oxide and H.sub.2 gas; and (I) recovering the electrical energy produced.

Electrochemical energy conversion and storage system

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

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Pittsburgh, PA, United States of America

Roswell J Ruka